Just to provide some context as someone who played the hell out of 2020 (on gamepass) and is looking forward to buying 2024 minute 1 and then figuring out how to keep a cat from fucking up a HOTAS sled for minutes 2-900:

The install is small because that is just the core game. Theoretically, that is all you need and it contains the meshes/logic for meshes and plane textures and so forth. You will then stream map data as you play and cache that. So the first time you take off at Pyongyang International it will take a bit of time to load but subsequent trips will be super fast.

That said… you will almost assuredly download the world packs. This is the much more hand crafted cities and airports so you can genuinely feel like you are flying over Paris or escaping from London Heathrow’s international terminal and so forth. Or just to fix some weirdness because of a building layout near a river. And those world packs get big.

Before I switched over to linux for full time gaming? My PC install of MSFS 2020 was probably 100-200 GB on its own just from all the updates?